150 THE ASCOMYCETES 



gencm are lacking. Perhaps all may as well be regarded as 

 Taphrina, ^\■ith host relationship as the basis for specific sepa- 

 rations. 



LITERATURE CITED 



FiTZPATRicK, R. E., "The life history and parasitism of Taphrina deforrnans,'' 



Sci. Agr., 14: 305-326, 1934. 

 GiESENHAGEN, K., "Die Entwicklungsreihen der parasitischen Exoasceen," 



Flora, 81:267-361, 1895. 

 Ju£L, H. O., "Cytologische Pilzstudicn. II. Zur Kenntnis einiger Hemi- 



asceen," Ncrca Acta Regiae Soc. Sci. Upsaliensis, IV, S: 1-43, 1921. 

 Klebahn, H., ''Infektionsversuche mit Taphrijia tosquinetii,^'' Ber. dent. 



botan. Ges., ^7:108-113, 1923. 

 .Martin, Ella M., "Studies on the morphology and cytology of Taphrina 



coryli Nishida," Trans. Wis. Acad. Sci., 2i: 345-356, 1924. 

 "Cultural and morphological studies of some species of Taphrina," 



Phytopathology, 15:61-16, 1925. 

 "The morphology and cytology of Taphrina defor?77a77s,^'' Am. J. Botany, 



27:743-751, 1940. 

 Mix, a. J., "Biological and cultural studies of Exoasciis deformans,^'' Phy- 

 topathology, 14:211-233, 1924. 

 Pierce, N. B., "Peach-leaf curl. Its nature and treatment," U. S. Dept. Agr., 



Div. Veg. Physiol. Path., Bull. 20: 11-204, 1900. 

 Sadebeck, R., "Die parasitischen Exoasceen, eine Monographic," Jahrb. 



Hamburg iviss. Anst., 10: 5-110, 1893. 

 Wiebex, Magdalene, "Die Infektion, die Myceluber\yinterung, und die 



Kopulation bei Exoasceen," Forsch. Gebiete Pfianzenk. limmmi. Pflanz- 



enr., 3: 139-176, 1927. 



EUASCOMYCETES 



For convenience the Euascomycetes may be arbitrarily sub- 

 divided into the Plectomycetes, Pyrenomycetes, and Discomy- 

 cetes. The Plectomycetes include those in which the asci are 

 irregularly arranged within a closed ascocarp or cleistothecium; 

 the Pyrenomycetes, those with asci reg^ularly arranged within an 

 ostiolate ascocarp or perithecium; and the Discomycetes, those 

 with asci regularly arranged within a widely opened or discoid 

 ascocarp or apothecium. Groups of Ascomycetes occur, to be 

 sure, that are intermediate between these arbitrary groupings or 

 that are in some respects aberrant. 



The fact that such groupings are arbitrary becomes all too 

 apparent when an attempt is made to locate in keys certain of 

 the Perisporiales, some of which are said to be ostiolate; the 



